Adds deterministic tenant mapping source semantics by persisting mapping_source (auto vs override) on sdk_tenant_databases with a backfill migration, updates runtime/management/legacy APIs and dashboard UI to expose the source, and introduces a new management “effective routing” endpoint for tenant routing diagnostics and eligibility decisions. This improves clarity and safety around routing/provisioning behavior (including gating disabling to override mappings) and provides better tooling for debugging routing outcomes, but it carries risk around the DB migration/backfill and any misclassification of legacy rows (metadata-based fallback) potentially affecting provisioning/disable flows and routing decisions.